The effect of Ge precursor on the heteroepitaxy of Ge _{1− <i>x</i>} Sn <i> _x </i> epilayers on a Si (001) substrate

Abstract

Abstract The heteroepitaxial growth of Ge 1− x Sn x on a Si (001) substrate, via a relaxed Ge buffer, has been studied using two commonly available commercial Ge precursors, Germane (GeH 4 ) and Digermane (Ge 2 H 6 ), by means of chemical vapour deposition at reduced pressures (RP-CVD). Both precursors demonstrate growth of strained and relaxed Ge 1− x Sn x epilayers, however Sn incorporation is significantly higher when using the more reactive Ge 2 H 6 precursor. As Ge 2 H 6 is significantly more expensive, difficult to handle or store than GeH 4 , developing high Sn content epilayers using the latter precursor is of great interest. This study demonstrates the key differences between the two precursors and offers routes to process optimisation which will enable high Sn content alloys at relatively low cost.